CodePen
CodePen is a browser-based integrated development environment focused on front-end web technologies. It allows users to write and execute HTML, CSS, and JavaScript in real-time, providing an immediate visual preview of the output. It serves as a platform for sharing code snippets, known as Pens, and projects, facilitating collaboration and learning within the web development community. It supports various preprocessors and libraries for streamlined front-end prototyping and experimentation.
Checked on Oct 19, 2026.
Alternative resources
Quokka
A live scratchpad for JavaScript and TypeScript that runs code immediately as you type within your code editor.
Python Playground
Fast and convenient Python compiler and editor Chrome extension that lets you run and test Python code directly in your browser popup.
Console Ninja
A debugging tool that displays console logs, runtime errors, and network requests directly in your code editor.